The present invention relates to a chuck for a bit and, more particularly, to a chuck for releasably receiving a bit such as a screwdriver bit.
Various chucks have been developed to allow quick change of a bit such as a screwdriver bit. A typical quick-change chuck includes a body having a first end coupled to a wrench or a screwdriver handle and a second end with a groove into which a shank of a bit is removably mounted. A sleeve is mounted around the body and movable along a longitudinal axis of the body between a coupling position in which a ball is engaged with the shank of the bit and, thus, retains the shank in place and a releasing position in which the ball is disengaged from the shank to allow removal or mounting of the bit. A spring is provided to bias the sleeve to the coupling position. An example of such a chuck is disclosed in U.S. Pat. No. 4,629,375. However, the chuck disclosed in U.S. Pat. No. 4,629,375 requires an end ring to prevent the sleeve from disengaging from the shank, leading to an increase in the total weight of the chuck as well as the costs. Furthermore, the bit is not engaged with any member and may fall freely when the sleeve is in the releasing position, leading to problems during replacement of the bit. In an approach to avoid falling of the bit, a magnet is mounted inside the body for attracting the bit. However, such a device can not be utilized in places having electronic equipment, for the magnet will interfere in operation of the electronic equipment. Further, the chucks are usually utilized in an environment with oil such that the fingers of a user often slip and, thus, can not effectively move the sleeve to the releasing position, leading to problems during mounting or replacement of bits. Furthermore, it is well known that when using a tool to tighten or loosen a fastener such as a screw, rotating the screw in a loose state through operation of the tool is troublesome and inefficient.
Thus, a need exists for a chuck that allows easy removal of the bit and that allows rapid rotating of the chuck to rapidly rotate the fastener in a loose state.